E2: Neuromuscular process of muscular contractions

Question 1

when can a skeletal muscle contract?

Answer 1

when stimulated by electrical impulses from a CNS

Question 2

what are motor neurones?

Answer 2

-specialised cells that transmit nerve impulses from the CNS in the brain and spinal cord to the muscle fibres
-the nerve that connects to the muscle fibre

Question 3

Whats the CNS made up of?

Answer 3

-cell body
-axons
-motor end plate

Question 4

where is the cell body located?

Answer 4

in the spinal cord

Question 5

where is the cell body located?

Answer 5

in the spinal cord

Question 6

what do axons do?

Answer 6

branch off the cell body and send impulses to the motor end plates

Question 7

whats a motor end plate?

Answer 7

where the action potential from an action travels to stimulate a muscle

Question 8

what makes up a motor unit?

Answer 8

motor neurone + muscle fibres
-a motor neurone provides muscle fibres with a signal

Question 9

whats the synapse inbetween the motor neurone and the muscle fibre called?

Answer 9

Neuromuscular junction

Question 10

what happens to a signal when it comes to the end plate of a motor neurone?

Answer 10

the impulse crosses the junction to activate the muscle fibre

Question 11

what is a synapse?

Answer 11

a connection point between 2 neurones

Question 12

What is the nuromuscular junction?

Answer 12

-a synapse between motor neurone and muscle fibre
-converts electrical impulses into electrical activity in the muscle fibre.

Question 13

What is a neurotransmitter?

Answer 13

a chemical messanger in the body, their job is to transmit signals from nerve cells to target cells(muscle fibre)

Question 14

what is a acetylcholine?

Answer 14

a chemical transmitter/neurotransmitter that is responsible for muscular contraction

Question 15

what is action potential?

Answer 15

the electrical impulse that makes the muscle contract

Question 16

what is the flow diagram of the neuromuscular process of muscular contractions?

Answer 16

nervous impulse->
arrives at the neuromuscular junction->
acetylcholine is released->
action potential allows for muscle fibre to contract->
Muscle fibre contracts.

Question 17

what happens to the signal when it is received by the muscle fibre?

Answer 17

the signal is spread throughout the muscle fibre/myofibril in order for the whole muscle fibre to contract.

Question 18

when can action potential be made?

Answer 18

when there is enough acetylcholine

Question 19

true or false: motor neurones cause contractions of a number of different muscle fibres

Answer 19

true

Question 20

what is the name of the tubes that the signal travels down to reach the filaments/myofibril?

Answer 20

T-tubules

Question 21

how do thin filaments in myofibril contract?

Answer 21

slide across eachother

Question 22

whats a sarcomere?

Answer 22

the functional part of the myofibril which consists of I,A and H bands

Question 23

what is actin?

Answer 23

thin protein filament

Question 24

what is myosin?

Answer 24

thick protein filament

Question 25

what do calcium ions do in the process?

Answer 25

work within the neurotransmitter to send signals and facilitate the muscular contraction

Question 26

whats troponin?

Answer 26

a group of proteins found in skeletal muscle fibres to regulate muscle contractions

Question 27

what is tropomyosin?

Answer 27

contractile proteins which work with actin and myosin

Question 28

what is the Z line?

Answer 28

the line at the edge of each sarcomere

Question 29

whats the H zone?

Answer 29

zone which contains the myosin filament

Question 30

whats the A band?

Answer 30

zone that contains the length of the sarcomere with the myosin filaments and does not change size during contractions. It can can contain just the myosin filaments(resting) or contain both actin and myosin(contracting)

Question 31

whats the I band?

Answer 31

the zone around the Z lines and includes part of the 2 sarcomeres. It only contains actin filaments and gets smaller when muscles contract

Question 32

how does acetylcholine turn into action potential?

Answer 32

the acetylcholine receptors detect whether or not there is enough acetylcholine, if their is action potential is released

Question 33

whats a cross bridge?

Answer 33

when actin and myosin attatch

Question 34

whats ATP?

Answer 34

energy used to pull and contract the actin and myosin

Question 35

whats it called when myosin and actin attatch and move?

Answer 35

power stroke

Question 36

when does a muscle contraction engage?

Answer 36

when the action potential arrives at the neuromuscular junction?

Question 37

what does the action potential arriving at the neuromuscular junction trigger?

Answer 37

calcium ions to be released from the sarcoplasmic reticulum and starts the process

Question 38

What does the calcium ions attatch to?

Answer 38

the troponin

Question 39

when calcium attatches to troponin, what happens?

Answer 39

the troponin moves/changes the shape of the tropomyosin, therefore exposing the binding sites.

Question 40

what can happen now that the binding sites have been exposed?

Answer 40

the myosin can then bind to the actin and causes a cross bridge to be formed.Once the cross bridge has been formed the muscle can now contract.

Question 41

why will the muscle shorten during contraction?

Answer 41

because the myosin is pulling the actin in.

Question 42

the process of myosin pulling actin in can continue as long as what?

Answer 42

there is sufficient ATP

Question 43

when will the mysosin detatch?

Answer 43

once the process has stopped or theres isnt enough calcium or ATP

Question 44

what happens to the muscle once the contraction has stopped?

Answer 44

the muscle will relax and become longer

Question 45

what are the 3 different types of muscle contractions?

Answer 45

-isometric -concentric -eccentric

Question 46

what is a concentric contraction?

Answer 46

-contraction when the musle shortens and develops tension. -A movement must occur against gravity

Question 47

what happens to the origin and insertion during concentric contractions?

Answer 47

the origin and insertion move closer together.

Question 48

what is a eccentric contraction?

Answer 48

-contraction when the muscle lengthens to deelop tension -movement must occur in a downwards phase to resist gravity

Question 49

what happens to the origin and insertion during eccentric contractions?

Answer 49

the origin and insertion move further apart from each other

Question 50

Whats a isometric contraction?

Answer 50

-“iso” means it does not change under tension-if the contraction creates tension but stays the same length then its isometric.

Question 51

when does an isometric contraction occur?

Answer 51

when the body is being fixed in 1 position